A medical error is a preventable adverse effect of care, whether or not it is evident or harmful to the patient. This might include an inaccurate or incomplete diagnosis or treatment of a disease, injury, syndrome, behavior, infection, or other ailment.


A medical error occurs when a health-care provider chooses an inappropriate method of care or improperly executes an appropriate method of care. Medical errors are often described as human errors in healthcare.[1]

However, medical error definitions are subject to debate, as there are many types of medical error from minor to major,[2] and causality is often poorly determined.[3]


A 2000 Institute of Medicine report estimated that medical errors are estimated to result in about between 44,000 and 98,000 preventable deaths and 1,000,000 excess injuries each year in U.S. hospitals.[4][5][6]

Some researchers questioned the accuracy of the IOM study, criticizing the statistical handling of measurement errors in the report,[7] significant subjectivity in determining which deaths were "avoidable" or due to medical error, and an erroneous assumption that 100% of patients would have survived if optimal care had been provided.[8] A 2001 study in the Journal of the American Medical Association of seven Department of Veterans Affairs medical centers estimated that for roughly every 10,000 patients admitted to the subject hospitals, one patient died who would have lived for three months or more in good cognitive health had "optimal" care been provided.[8]

A 2006 follow-up to the IOM study found that medication errors are among the most common medical mistakes, harming at least 1.5 million people every year. According to the study, 400,000 preventable drug-related injuries occur each year in hospitals, 800,000 in long-term care settings, and roughly 530,000 among Medicare recipients in outpatient clinics. The report stated that these are likely to be conservative estimates. In 2000 alone, the extra medical costs incurred by preventable drug related injuries approximated $887 millionTemplate:Mdashand the study looked only at injuries sustained by Medicare recipients, a subset of clinic visitors. None of these figures take into account lost wages and productivity or other costs.[9]

According to a 2002 Agency for Healthcare Research and Quality report, about 7,000 people were estimated to die each year from medication errors - about 16 percent more deaths than the number attributable to work-related injuries (6,000 deaths). Medical errors affect one in 10 patients worldwide. One extrapolation suggests that 180,000 people die each year partly as a result of iatrogenic injury.[10] One in five Americans (22%) report that they or a family member have experienced a medical error of some kind.[11]

Difficulties in measuring frequency of errors

About 1% of hospital admissions result in an adverse event due to negligence.[12] However, mistakes are likely much more common, as these studies identify only mistakes that led to measurable adverse events occurring soon after the errors. Independent review of doctors' treatment plans suggests that decision-making could be improved in 14% of admissions; many of the benefits would have delayed manifestations.[13] Even this number may be an underestimate. One study suggests that, in the United States, adults receive only 55% of recommended care [14]. At the same time, a second study found that 30% of care in the United States may be unnecessary.[15] For example, if a doctor fails to order a mammogram that is past due, this mistake will not show up in the first type of study.[12] And because no adverse event occurred during the short follow-up of the study, the mistake also would not show up in the second type of study,[13] because only the principal treatment plans were critiqued. However, the mistake would be recorded in the third type of study. If a doctor recommends an unnecessary treatment or test, it may not show in any of these types of studies.


See also Healthcare error proliferation model

Medical errors are associated with inexperienced physicians and nurses, new procedures, extremes of age, and complex or urgent care.[16] Poor communication (whether in one's own language or, as may be the case for medical tourists, another language), improper documentation, illegible handwriting, inadequate nurse-to-patient ratios, and similarly named medications are also known to contribute to the problem. Patient actions may also contribute significantly to medical errors. Falls, for example, may result from patients' own misjudgements. Human error has been implicated in nearly 80 percent of adverse events that occur in complex healthcare systems. The vast majority of medical errors result from faulty systems and poorly designed processes versus poor practices or incompetent practitioners.[17]

Healthcare complexity

Complicated technologies, powerful drugs, intensive care, and prolonged hospital stay can contribute to medical errors.

System and process design

In 2000, The Institute of Medicine released "To Err Is Human," which asserts that the problem in medical errors is not bad people in health care—it is that good people are working in bad systems that need to be made safer.[18]

Poor communication and unclear lines of authority of physicians, nurses, and other care providers are also contributing factors.[19] Disconnected reporting systems within a hospital can result in fragmented systems in which numerous hand-offs of patients results in lack of coordination and errors.[20]

Other factors include the impression that action is being taken by other groups within the institution, reliance on automated systems to prevent error.,[21] and inadequate systems to share information about errors, which hampers analysis of contributory causes and improvement strategies.[22] Cost-cutting measures by hospitals in response to reimbursement cutbacks can compromise patient safety.[23] In emergencies, patient care may be rendered in areas poorly suited for safe monitoring. The American Institute of Architects has identified concerns for the safe design and construction of health care facilities.[24] Infrastructure failure is also a concern. According to the WHO, 50% of medical equipment in developing countries is only partly usable due to lack of skilled operators or parts. As a result, diagnostic procedures or treatments cannot be performed, leading to substandard treatment.

The Joint Commission's Annual Report on Quality and Safety 2007 found that inadequate communication between healthcare providers, or between providers and the patient and family members, was the root cause of over half the serious adverse events in accredited hospitals.[25] Other leading causes included inadequate assessment of the patient's condition, and poor leadership or training.

Competency, education, and training

Variations in healthcare provider training & experience[19][26] and failure to acknowledge the prevalence and seriousness of medical errors also increase the risk.[27][28] The so-called July effect occurs when new residents arrive at teaching hospitals, causing an increase in medication errors according to a study of data from 1979-2006.

Human factors and ergonomics

Sleep deprivation has also been cited as a contributing factor in medical errors. One study found that being awake for over 24 hours caused medical interns to double or triple the number of preventable medical errors, including those that resulted in injury or death.[29] The risk of car crash after these shifts increased by 168%, and the risk of near miss by 460%.[30] Interns admitted falling asleep during lectures, during rounds, and even during surgeries.[30]

Practitioner risk factors include fatigue[31][32][33] and depression and burnout.[34] Factors related to the clinical setting include diverse patients, unfamiliar settings, time pressures, and increased patient to nurse staffing ratio increases.[35] Drug names that look alike or sound alike are also a problem.[36]

Examples of errors

Errors can include misdiagnosis or delayed diagnosis, administration of the wrong drug to the wrong patient or in the wrong way, giving multiple drugs that interact negatively, surgery on an incorrect site, failure to remove all surgical instruments, failure to take the correct blood type into account, or incorrect record-keeping.

Errors in HIV diagnosis

A large study reported several cases where patients were wrongly told that they were HIV-negative when the physicians erroneously ordered and interpreted HTLV (a closely related virus) testing rather than HIV testing. In the same study, >90% of HTLV tests were ordered erroneously.[37]

Misdiagnosis of psychological disorders

Regarding mental illnesses, sufferers of dissociative identity disorder usually have psychiatric histories that contain three or more separate mental disorders and previous treatment failures.[38] The disbelief of some doctors around the validity of dissociative identity disorder may also add to its misdiagnosis.[38]

Female sexual desire sometimes used to be diagnosed as Female hysteria.

Sensitivities to foods and food allergies risk being misdiagnosed as the anxiety disorder Orthorexia.

Studies have found that bipolar disorder has often been misdiagnosed as major depression. Its early diagnosis necessitates that clinicians pay attention to the features of the patient's depression and also look for present or prior hypomanic or manic symptomatology.[39]

The misdiagnosis of schizophrenia is also a common problem. There may be long delays of patients getting a correct diagnosis of this disorder.[40]

The DSM-5 field trials included "test-retest reliability" which involved different clinicians doing independent evaluations of the same patient—a new approach to the study of diagnostic reliability.[41]

Most common misdiagnoses

A 2009 meta-analysis identified the 5 most commonly mis-diagnosed diseases as: infection, neoplasm, myocardial infarction, pulmonary emboli, and cardiovascular disease.[42] Physician familiarity with this information is variable.[43]

Outpatient vs. inpatient

Misdiagnosis is the leading cause of medical error in out patient facilities. Since the National Institute of Medicine’s 1999

After an error has occurred

Mistakes can have a strongly negative emotional impact on the doctors who commit them.[45][46][47][48]

Recognizing that mistakes are not isolated events

Some doctors recognize that adverse outcomes from errors usually do not happen because of an isolated errors and actually reflect system problems.[49] This concept is often referred to as the Swiss Cheese Model.[50] This is the concept that there are layers of protection for clinicians and patient to prevent mistakes from occurring. Therefore, even if a doctor or nurse makes a small error (incorrect dose of drug written on a drug chart by doctor) this is picked up before it actually affects patient care (pharmacist checks the drug chart and makes rectifies the error).[50] Such mechanisms include: Practical alterations (e.g.-medications that cannot be given IV, are fitted with tubing which means they cannot be linked to an IV even if a clinician makes a mistake and tries to),[51] systematic safety processes (e.g.- all patients must have a Waterlow score assessment and falls assessment completed on admission),[51] training programmes/continuing professional development courses [51] are measures that may be put in place.

There may be several breakdowns in processes to allow one adverse outcome.[52] In addition, errors are more common when other demands compete for a physician's attention.[53][54][55] However, placing too much blame on the system may not be constructive.[49]

Placing the practice of medicine in perspective

Essayists imply that the potential to make mistakes is part of what makes being a physician rewarding and without this potential the rewards of medical practice would be less. Laurence states that "Everybody dies, you and all of your patients. All relationships end. Would you want it any other way? [...] Don't take it personally"[56] Seder states "[...] if I left medicine, I would mourn its loss as I've mourned the passage of my poetry. On a daily basis, it is both a privilege and a joy to have the trust of patients and their families and the camaraderie of peers. There is no challenge to make your blood race like that of a difficult case, no mind game as rigorous as the challenging differential diagnosis, and though the stakes are high, so are the rewards."[57]

Disclosing mistakes

Forgiveness, which is part of many cultural traditions, may be important in coping with medical mistakes.[58]

Disclosure to oneself

Inability to forgive oneself may create a cycle of distress and increased likelihood of a future error.[59]

However, Wu et al suggest "...those who coped by accepting responsibility were more likely to make constructive changes in practice, but [also] to experience more emotional distress."[60] It may be helpful to consider the much larger number of patients who are not exposed to mistakes and are helped by medical care.[57]

Disclosure to patients

Gallagher et al state that patients want "information about what happened, why the error happened, how the error's consequences will be mitigated, and how recurrences will be prevented."[61] Interviews with patients and families reported in a 2003 book by Rosemary Gibson and Janardan Prasad Singh, that those who have been harmed by medical errors face a "wall of silence" and "want an acknowledgement" of the harm.[62] With honesty, "healing can begin not just for the patients and their families but also the doctors, nurses and others involved." Detailed suggestions on how to disclose are available.[63]

A 2005 study by Wendy Levinson of the University of Toronto showed surgeons discussing medical errors used the word "error" or "mistake" in only 57 per cent of disclosure conversations and offered a verbal apology only 47 per cent of the time.[64]

Patient disclosure is important in the medical error process. The current standard of practice at many hospitals is to disclose errors to patients when they occur. In the past, it was a common fear that disclosure to the patient would incite a malpractice lawsuit. Many physicians would not explain that an error had taken place, causing a lack of trust toward the healthcare community. In 2007, 34 states passed legislation that precludes any information from a physician’s apology for a medical error from being used in malpractice court (even a full admission of fault).[65] This encourages physicians to acknowledge and explain mistakes to patients, and keeping an open line of communication.

The American Medical Association's Council on Ethical and Judicial Affairs states in its ethics code:

"Situations occasionally occur in which a patient suffers significant medical complications that may have resulted from the physician's mistake or judgment. In these situations, the physician is ethically required to inform the patient of all facts necessary to ensure understanding of what has occurred. Concern regarding legal liability which might result following truthful disclosure should not affect the physician's honesty with a patient."

From the American College of Physicians Ethics Manual:[66]

“In addition, physicians should disclose to patients information about procedural or judgment errors made in the course of care if such information is material to the patient's well-being. Errors do not necessarily constitute improper, negligent, or unethical behavior, but failure to disclose them may.”

However, "there appears to be a gap between physicians' attitudes and practices regarding error disclosure. Willingness to disclose errors was associated with higher training level and a variety of patient-centered attitudes, and it was not lessened by previous exposure to malpractice litigation".[67] Hospital administrators may share these concerns.[68]

Consequently, in the United States, many states have enacted laws excluding expressions of sympathy after accidents as proof of liability; however, "excluding from admissibility in court proceedings apologetic expressions of sympathy but not fault-admitting apologies after accidents"[69]

Disclosure may actually reduce malpractice payments.[70][71]

Disclosure to non-physicians

In a study of physicians who reported having made a mistake, disclosing to non-physicians sources of support may reduce stress more than disclosing to physician colleagues.[72] This may be due to the physicians in the same study, when presented with a hypothetical scenario of a mistake made by another colleague, only 32% physicians would have unconditionally offered support. It is possible that greater benefit occurs when spouses are physicians.[73]

Disclosure to other physicians

Discussing mistakes with other doctors is beneficial.[49] However, doctors may be less forgiving of each other.[73] The reason is not clear, but one essayist has admonished, "Don't Take Too Much Joy in the Mistakes of Other Doctors."[74]

Disclosure to the physician's institution

Disclosure of errors, especially 'near misses' may be able to reduce subsequent errors in institutions that are capable of reviewing near misses.[75] However, doctors report that institutions may not be supportive of the doctor.[49]

Use of rationalization to cover up medical errors

Based on anecdotal and survey evidence, Banja[76] states that rationalization (making excuses) is very common amongst the medical profession in covering up medical errors.

By presence of to the patient

A survey of more than 10,000 physicians in the United States came to the results that, on the question "Are there times when it's acceptable to cover up or avoid revealing a mistake if that mistake would not cause harm to the patient?", 19% answered yes, 60% answered no and 21% answered it depends. On the question "Are there times when it is acceptable to cover up or avoid revealing a mistake if that mistake would potentially or likely harm the patient?", 2% answered yes, 95% answered no and 3% answered it depends.[77]

Cause-specific preventive measures

Traditionally, errors are attributed to mistakes made by individuals who may be penalized for these mistakes. The usual approach to correct the errors is to create new rules with additional checking steps in the system, aiming to prevent further errors. As an example, an error of free flow IV administration of heparin is approached by teaching staff how to use the IV systems and to use special care in setting the IV pump. While overall errors become less likely, the checks add to workload and may in themselves be a cause of additional errors.

A newer model for improvement in medical care takes its origin from the work of W. Edwards Deming in a model of Total Quality Management. In this model, there is an attempt to identify the underlying system defect that allowed the opportunity for the error to occur. As an example, in such a system the error of free flow IV administration of Heparin is dealt with by not using IV heparin and substituting subcutaneous administration of heparin, obviating the entire problem. However, such an approach presupposes available research showing that subcutaneous heparin is as effective as IV. Thus, most systems use a combination of approaches to the problem.

In specific specialties

The field of medicine that has taken the lead in systems approaches to safety is anaesthesiology.[78] Steps such as standardization of IV medications to 1 ml doses, national and international color-coding standards, and development of improved airway support devices has made anesthesia care a model of systems improvement in care.

Pharmacy professionals have extensively studied the causes of errors in the prescribing, preparation, dispensing and administration of medications. As far back as the 1930s, pharmacists worked with physicians to select, from amongst many options, the safest and most effective drugs available for use in hospitals.[79] The process is known as the Formulary System and the list of drugs is known as the Formulary. In the 1960s, hospitals implemented unit dose packaging and unit dose drug distribution systems to reduce the risk of wrong drug and wrong dose errors in hospitalized patients;[80] centralized sterile admixture services were shown to decrease the risks of contaminated and infected intravenous medications;[81] pharmacy computers screened each patient’s medication list for drug-drug interactions;[82] and, pharmacists provided drug information and clinical decision support directly to physicians to improve the safe and effective use of medications.[83] Pharmacists are recognized experts in medication safety and have made many contributions that reduce error and improve patient care over the last 50 years. More recently, governments have attempted to address issues like patient-pharmacists communication and consumer knowledge through measures like the Australian Government's Quality Use of Medicines policy.

Legal procedure

Main article: Medical malpractice

Standards and regulations for medical malpractice vary by country and jurisdiction within countries. Medical professionals may obtain professional liability insurances to offset the risk and costs of lawsuits based on medical malpractice.

Methods to improve safety and reduce error

Further information: Patient safety

Medical care is frequently compared adversely to aviation; while many of the factors that lead to errors in both fields are similar, aviation's error management protocols are regarded as much more effective.[84] Safety measures include informed consent, the availability of a second practitioner's opinion, voluntary reporting of errors, root cause analysis, reminders to improve patient medication adherence, hospital accreditation, and systems to ensure review by experienced or specialist practitioners[85]

Reporting requirements

In the United States reporting medical errors in hospitals is a condition of payment by Medicare.[86] An investigation by the Office of Inspector General, Department of Health and Human Services released January 6, 2012 found that most errors are not reported and even in the case of errors that are reported and investigated changes are seldom made which would prevent them in the furture. The investigation revealed that there was often lack of knowledge regarding which events were reportable and recommended that lists of reportable events be developed.[87]

Misconceptions of medical error

Common misconceptions about adverse events are the following, and in parentheses are the arguments and explanations against those misconceptions:

  • "Bad apples" or incompetent health care providers are a common cause. (Although human error is commonly an initiating event, the faulty process of delivering care invariably permits or compounds the harm, and is the focus of improvement.[6]
  • High risk procedures or medical specialties are responsible for most avoidable adverse events. (Although some mistakes, such as in surgery, are harder to conceal, errors occur in all levels of care.[6] Even though complex procedures entail more risk, adverse outcomes are not usually due to error, but to the severity of the condition being treated.).[19][88] However, USP has reported that medication errors during the course of a surgical procedure are three times more likely to cause harm to a patient than those occurring in other types of hospital care.[20]
  • If a patient experiences an adverse event during the process of care, an error has occurred. (Most medical care entails some level of risk, and there can be complications or side effects, even unforeseen ones, from the underlying condition or from the treatment itself.[89]

See also


Further reading

External links

  • DMOZ
  • Medical Errors & Patient Safety from U.S. Dept. of Health & Human Services, Agency for Healthcare Research and Quality
  • Dead by Mistake - Dead by Mistake - Hearst Newspapers Report, August 2009
  • Report to the President on Medical Errors from February 2000
  • Information on Medical Errors from medstat-info.org
  • Consumers Union May 19, 2009
  • The Savvy Patient Toolkit to help minimize errorsde:Behandlungsfehler